Pulse-echo direction and ranging device



June 12, 1951 LIPSON r AL 2,556,201

PULSE-ECHO DIRECTION AND RANGING DEVICE Filed Jan. 15, 1944' 3 4Sheets-Sheet '1 Elma/who 450N420 9. LIPS a/v 4AF3Q0 WPETCHIFT A f Z M i.B. LIPSON r AL PULSE-ECHO DIRECTION AND meme DEVICE I00 Grass June 12,1951.

Filed Jan. 15, 1944' r s {w re W WW w A n n. 1 :i A n A L HEAIVSLEO/V420 5. L/PSO/V ALFPE 0 I4. 1 5 TCHAVFT June 12, 1951 L. B. LIPSONET AL 2,556,201

PuLsE-Ecuo DIRECTION AND RANGING DEVIGE Filed Jan. 15, 1944 4 Sheets-Sheet 4 rotating antenna and radiator are uniquely con-" nected throughthe various electronic circuits, presently described,,to a cathode raytube having a beam which sweeps. circular ,'and horizontal paths inrapidly alternating succession so that the screen of the tube presentsthe appearance of having a circular and horizontal line at all times.During each interval in Which'the beam is sweeping the circular path, itis synchronized in rotational speed with the rotationalspeed of" theantenna. Furthermore, the; antenna is so connected to the tube thatwhenever the antenna picks up an impulse-echo a correspondingdeflection, defocused spot or other visible indication will appear alongthe circular trace and since the trace and antenna are in a senserotating together, this spot or other indication will .appear at a pointalong the circular trace: which corresponds to the angular positionof'the antenna at the moment the signal is picked up. In addition theantenna andrad-i'ator are both connected to the tube in such a mannerthatthe outgoing impulse and the impulse-echo will both produce spaceddeflections along'the horizontal trace such that the distance betweenthem is a measure of the distance between the obstacle and the radiator.

Referring now in more detail to the drawings A designates the antennaradiator assembly forming a part of our invention and comprises an outerhousing I constructed preferably of synthetic plastic or :any otherstructurally strong radiation-transparent material] It is desirable,although not absolutely essential, that the housing I be formed in thestreamlined shape shown, having a somewhat ellipsoidal shell 2integrally connected on its underface to a neck 3 of circularcross-section and having a flaringskirt-like lower portion 4 forsecurement in any conventional manner to the roof or any other suitablepoint of attachment on the aeroplane, helicopter or vehicle (not shown)It should be noted in this connection, however, that the antennaassembly A should preferably be so located that none of the stationarystructure or moving parts of the aeroplane, helicopter or vehicle willbe in the path of the emitted impulses.

Peripherally secured within the housing neck 3 are two identical" andopposed frusto-conical metal members 5, 6 axially spaced from each otherat their apices in the provision of a narrow gap 9, and symmetricallydisposed with the gap 9 is a small vertical exciter antenna 1, forming,together with the members 5; 6, a so-called biconical horn typeradiator. Extending axially through the members 5, 6 and upwardly intothe shell 2 is a hollow Bakelite shaft Bprovided at its upper end with arigidly secured triangular plate 9 formed of polystyrene or other.suitable material, the latter being so positioned that its .center ofgravity is coincident with the axisof rotation of the shaft 8. Alongtwo'of itslateral edges, the triangular plate 9 is provided with aplurality of equally spaced copper rods l0 extending through, andprojecting equidistantly, on either side thereoff. Also mounted'inv andprojecting on either side of the plate 9 are axially aligned'copper rodsII, II forming the two elements of a dipole receiving antenna,respectively connected to a coaxial cable having an inner conductor l2and. an outer conducting sheath I3 and extending through the interior ofthe hollow Bakelite shaft 8. Various means such as slip rings or'goniometers may be employed at this point for-electricallyconnectingthe antenna to theiremainder of theappa- 4 ratus, but we have foundpreferable and, hence, have shown the conductor 12 and sheath 13 asbeing connected across a coil I4 which is in turn fixed to the shaft 8and is inductively coupled to a fixed coil l5, within which it rotates.Adjustably secured to the shaft for rotation therewith is a fiber disk16 which is provided adjacent its peripheral margin with a magnetizedhigh permeability insert l1. Suitably mounted adjacent to the disk I6 isa solenoid I '8 so arranged that the lines of flux associated with itswindings will be changed sharply each time the insert [1 of the rotatingdisk [6 passes it.

At its lower end the shaft 8 is connected through a conventional gearbox 19 to an antenna motor 20' which is in turn connected thru asuitable motor speed control 2l to any suitable source of electricpower. It will, of course, be apparent that the length and arrangementof the shaft 8 should be such as to permit convenient location of thecoil 14, I5, the disk I6 and the motor 20 within the interior of theaeroplane, helicopter or vehicle.

The motor control 2| is mounted upon a dashboard or instrument panel 23and the control knob 24 located accessibly upon the face thereof forconvenient manipulation by the operator. Also mounted upon the panel 23is a main switch .25 of any conventional design and a focusing andintensity control 26 preferably consisting of two concentrically mountedvariable resistors 21, 28 having aligned control knobs 29, 30respectively. The panel 23 is also provided with a circular opening 3|and secured behind the panel is a cathode ray tube 32 having its forwardor screencontaining end 33 presented through the panel opening 3| andheld therein by means of an annular shock-absorbing ring 34. Etched orotherwise marked upon the outer face of the tube 32 are a circular scale35 graduated in degrees for indicating relative azimuth and a horizontalscale 36 graduated in feet or yards for indicating lineal distance, allas best seen in Fig. 2.

The cathode ray tube 32 is also internally provided in conventionalmanner with four counterposed deflection plates 31, 38, 39, 40, anaccelerating anode 4 l a focusing anode 42, a grid or modulatingelectrode 43 and a cathode or filament M.

The antenna-radiator assembly A is electrically connected to the cathoderay tube 32 through a series of inter-connected and cooperative circuitsas schematically shown in Fig. 3, and comprising a transmitter 45, areceiver 46, a keyer 41, an impulse selector 48, a saw-tooth oscillator49, a sine-wave oscillator 50, a high-gain amplifier 5| and atransformer-output amplifier 52. I

It may be pointed out in this connection that the impulse selector 48includes four synchronized blanking means. Any conventional blankingcircuit may be employed, the simplest and most commonly recognized formof which comprises essentially a, vacuum tube amplifier which isconverted so that it may be alternately rendered conducting ornon-conducting by means of a square wave generator which controls thebias of said amplifier. The first blanking means is for receiving theoutput of the saw-tooth oscillator 49, the second blanking means is forreceiving the output of the sine-wave oscillator 50, the third blankingmeans is for receiving the impulse created when the magnetized highpermeability insert I5 induces a current in solenoid l8, and the fourthblanking means is for receiving the attenuated output of thejkeyer 41.In addition, the im,

pulse selector 48 includes a switching circuit for.

alternatelygimposingttheroutput -.of. theireceiveni 46 uponithe: firsti-blankingi-means and upon the inputiof the amplifier-52..Theoperationhof the imp'ulseselectorAB may best be seenrby refer encehtoFigure The .inputand output'leads of. the four blanking means iareiindicated by arrows. going into and cominghout ofith'e.boxessrepresentsing the various-means. It ShOlll'dibQ noted-that; one input-lead andOIIEOlltPlltllefidDf: eacheof: the means in the impulse selectors isgrounded. o The--firstblanking is provided withvtwoichannelsg; Theiinput to channel I is throughle'adsnlfii and:;..:: 11 Cground) =theinput to channel: 2: is; througlrs. lead 400 andgrounda Theoutput fromchannel: I is throughlead llll' andrgroundr Thaoutputmt fromchannellthroughilead; I02 :and ground); The two channels of (the first;blanking: meansoperate-so as to pass-on to. leadsJBfindJBi,0r,b1ank.;.;outjtheloutputfof 5| and 46'..-*;Iheoutput;of 4E passes through the.switchingtmeans. before itiis go impressed; by meansof lead: 'Hlllandground on theifirsti blankingiz means; llleadi Q'Iahand: ground; g isprovided so that a square-wave. pulse'in thei.- proper phase is providedtothefirst ,andfourth blanking means. Thusswhen-the output, of 4 6 isimpressedon the firstblanking means, the proper pulseis providedltothe-first and fourth blanking means' so that theyeaaresconducting. The;p; fourth blankingmeanscby meansof input leads 5'! -'(ground.)irandv 58.andrsoutputglead 193-"; and groundiprovidesa.referenceapip d on thetracew t from the keyer-Jl]; Thei second blanking means I has twochanne1s.i!The inputz'toc-channel I is lead a 69 andaground.Theyinputofromch-anneliisleadV I0 and ground. The output; from channelis 1leady35 18 and ground Thexoutputzfrom'channel; 2 is lead-19 andground. Leadi9'8' and; ground -,pro vides aisquare wave pulse in theopposite; phase fromthat providedrby 91a: and groundolfor the,- properoperation 0f the second and third blank-, ing meansi. The secondblanking means byv means of input leads :59 and 10 and phase'shiftingnet1 work H 'and'i2 through output leads J8, 3 9,. and ground provides thecircular ,tracert During thissame interval, the third blanking means,throughg r, output leads all and 8| (ground) ,:is providing ref-R erencepip r from l8. Also during this.same-interval, the switchingmeans-hasiswitchedthe-out: putl of receiver. to output-leadl'fld ;and-=-|'!l5:- which connect .to leadse'BD and "8!, respectively.- Lead .99and ground is. 115611 170 synchronize the squarezlwavevgenerator intheiswitching means with'o'scil1ator50.

The exciter antenna 1 is connected by acoaxialr cable having an innerconductor 53 and concen trickconducting sheath 54 .to the output circuiof theltransmitter 45, the input. circuitiof which I is in turnconnected by leads 55, :E S- to the output; circuit of the keyer. 41.:Therattenuated output, of the keyer 41 is connectedby leads-51, 58 to othe fourth blanking meansgand the'input circuits: of the keyer 4T isconnected by leads 59,, '60 to selected output points-'vwithinthG'1S8.W-'t0,0thOSCEHPJ, 1ator-49 for imposing a. synchronizing:voltage. upon the keyer B1. The solenoid I-8 isconnectedmsg; as abovestated, to the third'fblanking:meanswf theimpulse selector-48 by leads6!;62 andsimilarly the coil 15 is'con'nectedby coaxial leads 5'3 64 to:the input circuit of theareceiverfl lfi which is in turn-connected onits output side-by leadsiES; =7 B6 to the switchingcircuit of theimpulse- :se-= lector l 8 V Thesaw-tooth oscillator 49' and sine-wave'05- c cil1ator;-5U are interconnected for synchronization by leads .1,68, and thesine-Wave= oscillator:515

50 is; itself;'connectedgthrough-,leads, 69,, :10 di- :1 rectlywto thesecondblankingrmeans of: the impulse selector 48, the leads 69, 10 beingbridged; by apha's'e shiftingnetwork consisting of a fixed resistor." Hconnected ,in series with Ta, fixed leapacitor 12. A lead 13 is taken:off between the resistance-fH-and condenser; 12- for connection toground; o Similarly the saw-tooth oscillator 49 is: 1

connected by leads'M, l5 tothe high-gain amplifier 5 l,1 which is inturn connected by the leads I6, 11 to the first blanking means of theimpulse selector148; 1'

The output from the first, second and fourth blankingmeans of theimpulse selector 48, as will presently -more fully appear; is imposedthrough;,: the leads' 118, 19 respectively upon the deflection 1 plates31, 38 of the cathode ray tube 32. Further the output of the thirdblanking means and one V outputphase of theswitchingcircuit. are50011-13 nected in common by leads 80, 8| to the-input 3.;circuit'ofamplifier52.

The output circuit of amplifier 52 is connected 42 andv a'slidingcontact 8 5 of the Variable resistor2'l, the latter being oonnectediatone: end-1., to the'variable resistor: 28 andat its otherv end v toone-. end of a fixed resistor whichis in turn; connected at its otherend to ground; The re' sistortZB is' connected at. its other end by lead8-6 H to the negative terminal of a high voltage powersource,rthe-vpositive terminal of which1is conv. nected to ground. Theslidingcontacttl of the resistor 28 is connected by lead 88 to the grid:or 1':- modulating electrode 43 and finallyya cathode, leadr;8 9 istaken ofi between the connected ends. of theresistors 21, 28andconnected to:the =cath'-' ode' 44. The plates 39, 40 and theaccelerating anode 4| are mutually. connected internally and connectedby a common lead 98 to ground. .1

Thekeyer 4! which, as has been above pointed out iis synchronized;with'the saw-tooth oscil-- lator 49., is designedto emit a pulse ofshort duration'rat the beginning of each saw-tooth oscillation-and thispulse is fed simultaneously intoy:

graphically in Fig. 4. It should be clearly under-:: stood" that thefour blanking means cooperate,

within the impulse selector 48, so that during a given time intervaleither the sine-wave or sawtoothiwave will be imposed upon thercathoderay tube. 32. Furthermore, .one outputrof the first blanking means isconnected, within the impulsev .1

selector, to ground and to lead 19 so that the saw-tooth oscillator,during the intervals of its transmission, will be imposed acrossdeflection plates-38,40. Similarly, the outputs of the sect 0nd blankingmeans is connected, Within the impulse selector 48, to leads l8, l9 andto ground so that the sine-wave oscillation, during the intervals of itstransmissiomwill be imposed across all fourrdefiection plates 31, 38,39,40.

Inasmuch as the sine-wave oscillator is associated with thephase-shifting network consisting of resistor H and capacitor E2, thephase shifted sine-wave outputs of thesecond blanking means when-fed tothe cathode ray tube 32, will:

ELCtqfiS a'circular sweep; likewise, the saw-tooth output of thefirstblanking-means will act as horizontal sweep,- Consequently the beam:willr 7 produce, on the sentitized screen, a circular trace t followedby a horizontal trace t as indicated in Fig. 2.

From Fig. 3 and the foregoing description it will be evident that thekeyer 41, the impulse selector 48 and the saw-tooth oscillator 49 areall synchronized by the sine-wave oscillator 50 so that the several waveforms depicted in Fig. 4 will be maintained in strict timed relation. It

. is also essential that the antenna motor 20 and the gear box [9 beselected and designed to rotate the antenna shaft 8 and its associatedparts at a speed which bears a fixed and calculated relationship to thefrequency of the sine-wave oscillator 50. For illustrative purposes inthe present description it may be assumed that antenna shaft 8 isrotating at a speed of 720 revolutions per minute and the sine-waveoscillator 50 has a frequency of twelve cycles per second so that thecircular sweep is in effect rotating at the same speed as the antennashaft 8. At the same time the saw-tooth oscillator 49 is oscillating at1200 cycles per second or 100 cycles for each cycle of the sine-waveoscillator 50 and the keyer 41 which is in efiect energized by thesaw-tooth oscillator 49 will emit 1200 pulses per second. The speed ofthe circular trace t is relatively slow in relation to the persistenceof vision of the human eye, hence, it is desirable that the screen 33 ofthe cathode ray tube 32 be a fairly long persistence screen so as toprevent flickerings or visually perceptible discontinuity of the image.

In operation, the main switch 25 is turned on energizing the entireapparatus and setting the antenna assembly in motion. The transmitter45, under control of the keyer 41 sends out short timed pulses in timedrelation to the frequency of the sine-wave oscillator 5E} as previouslydescribed and illustrated in Fig. 4. These impulses are emitted radiallyin all directions in a plane perpendicular to the axis of symmetry ofthe biconical horn radiators 5, 6. For most purposes, such as use inhelicopters for example, this axis of symmetry will always besubstantially vertical to the ground and, therefore, the radiationsemitted by the biconical horns 5, 6 will travel in a substantiallyhorizontal plane and the angle of divergency between the members 5, 6,should be such that the distance between the upper and lower limits ofthe radiation at the outer limit or range of the apparatus should besufficiently greater than the vertical height of the helicopter itselfas as to provide an adequate margin of safety above and below. If thisangle of divergence is too narrow, the emitted radiations may miss amountain peak which is only a few feet below the line of flight of thehelicopter and on the other hand if the angle of divergence is too greatthe emitted radiations may detect a mountain peak which is far below theline of flight of the helicopter, either result being obviouslyimpractical and undesirable. From this it will be seen that the angle ofdivergence should be selected with reference to the flying speed of thehelicopter and the range of the apparatus itself so as to achieve apractical result allowing an adequate but not excessive margin of safetyabove and below the line of flight of the helicopter.

When the timed pulses emitted by the biconical horn radiator encounteran obstacle, a return or impulse-echo will be reflected back to therotating dipole antenna H, H along a line corresponding to the azimuthor line of direction hetween the antenna and the obstacle. By reason ofthe fact that the dipole antenna H, II is placed within the angle of aso-called corner reflector, comprising plate 9 and rods II], it willonly pick up the signal during the instant in which its axis ofreception or directivity is aligned with the azimuth or line ofdirection of such incoming signal or. impulse-echo. This impulse-echowill be transmitted through the inductively coupled coils l4, l5 to thereceiver 46.

From the receiver 46, the impulses are transmitted through the leads 65,66 to the switching means within the impulse selector 48 and by theswitching means alternately transmitted to the transformer outputamplifier 52 and the first blanking means of the impulse selector 48.

Meanwhile the impulses from the keyer 41 are also transmitted to thefourth blanking means and super-imposed upon the saw-tooth wave at thevery beginning of each cycle. Therefore, during a selected interval inwhich the saw-tooth wave is being transmitted (the sine-wave beingblanked out during this interval) the horizontal trace it will appear onthe screen of the cathode ra tube 32 and a visable deflection or pip dwill appear at the left-hand end of the trace t providing a point ofreference for the measurement of lineal distance. Inasmuch as thesaw-tooth wave has a frequency of 1200 cycles, the time interval foreach cycle is approximately 833 microseconds and assuming that theequipment be designed for a range of two miles, the impulse-echo, ifreturning from maximum range, will consume about 20 microseconds. Forthis reason the high gain amplifier 5| is so adjusted as to stretch: thetheoretical length of the horizontal trace to about inches so that thefirst two inches (which will be within the size limitations of thescreen 33 and therefore visible) will be traced out in about 20microseconds. If the keyer controlled impulse sent out by thetransmitter 45 encounters an obstacle so that an impulse-echo returns,such impulse-echo will be picked up by the rotating dipole antenna IIand impressed through the switching means of the impuls selector 48 uponthe saw-tooth wave resulting in a second visible deflection or pip al inthe horizontal trace t Since the emitted impulse and its correspondingimpulse-echo travel at a finite speed there will be a definite time lagbetween the emission of the impulse and its return which is directlyproportional to the lineal distance between the obstacle and the antennall. Because of this time lag, the impulse-echo coming through thereceiver 46 will be impressed upon the saw-tooth wave at some finiteinterval of time after the beginning of its cycle. Consequently, the pip01 will be displaced to the right of the zero or reference pip d by adistance which is a direct measure of the lineal distance between theobstacle and the antenna I I. By providing a suitably calibrated scale36 on the face of cathode ray tube 32 it thus becomes possible to readthis lineal distance directly in terms of feet, yards, miles or an otherselected unit of measurement.

In the next succeeding interval the saw-tooth wave and its super-imposedpip forming impulses will be blanked out and the sine-wave will betransmitted through the second blanking means of the impulse selector 48to produce the circular trace t on the screen of the cathode ray tube32. Of course the intermittent impulses sent out by the transmitter 45under timed control of the keyer 41 will continue in unbroken sequence.I Since the keyer 4'! emitslOO pulses for each cycle of the-sine-waveoscillator, this-meansthat 100 the-antenna l l or in efiect- -l pu1se-'for-each3.6 of=-arcuate'movement; I'he. antenna H would-thereforebe-desisned to-have anaccuracy-or deduring eachrevol-utionfwill pick up atleast one of the impulse-echoes returning from a givenobstacle, no'matter what the azimuth 'or direction line to that objectmay be; Of course, the direc- I tion indication will only be accuratewithin 2 but for-navigationalpurposes in a helicopteror-simi- ='--la-rcraft,- this accuracy is more thanadequate. It will, of course, be'understood'that wherehigher accuracy is desired a higher frequencyrepeti- 1 cillator 49 and keyerl respectively together with -----anantenna of-much sharper ordefinitive selec'tivity. Thus, when theantenna ll reaches the -=--'position in which its axisisin line withtheazii muth of the impulse-echo-an impulse will be transmitted throughthe receiver to the switching means of the impulseselector 48 which;during this interval, is functioning to transmit the im- -pulse to thetransformer output amplifier 52 and such impulse is thusimpresseduponthefocusing anode 42 in serieswith the potential normallyderived through the contact arm 84 of the variable 1; "resistance 21,thereby defocusing the cathode beam so as to create adistinct dotorbright spot.

- Since the tracet and the antenna H are rotating together--the spotwill appear-at some point on thecircular trace t which corresponds tothe azimuth of the obstacle. For instance, if the cathode ray tube isgraduated circularly sothat the graduation T will correspond to a dead Jahead position, then an obstacle which is 45 oif to the right of theline of travel of the, helicopter will be indicated b a spot on-thetrace t 45 down to the right of the graduation r as shown at r in Fig.2. 5 Becausethe antenna motor 20, in the ordinary course of manufacturedarticles, cannot be made --to operate at a precisely constant speedwithout resort toveryexpensive automatic speed control devices, it isdesirable to provide asimple visual signal or indexing means to showwhen the motor and the circular sweep are properly synchronized. Such asignal can be employed in 'conjunction'with a suitable rheostat or othermanual motorspeed control 2 I. Accordingly, we provide the adjustablefiber disk l6 which is fixed to the rotating shaft '3 and carries themag- -netic insert ll. As the shaft 22 rotates, the magnetic field ofthe-insert l'lcuts the lines of flux associated with the conductorsmaking upthe solenoid l8-and induces a current in the coils 1 thereof sothat a very short impulse is fed through the leads BI, 62, into thethird blanking means' 'of the'impulse selector 4a and thence imposedupon the focusinganode 42 during each so-called sine-wave interval. -Thedisk [6 is preferably set upon the shaft 8 so that the insert I1 isdirectly to therear when the antenna tor: .the left iof the' graduationr as the ease :ma'y

- finitive selectivity ofapproximately :2" sothat it-'will' pick upanyimpulse-echo within anarc of -slightlym0re than 4'; -'Consec uently,theantenna tionrate may beemployed inthe-saw-tooth oslar sweep,theiindexing pipj will creep to the right "be; whereupon theoperator-can turn the motor *pulseswillbe sent out-during eachrevolution of speed control knobfl and'increase or decrease :thespeed-of the motor ZIJ-untilthe pip'returns and remains'at the properposition of coincidence with-graduation -r Asomewhat similar effect canbe obtained by fixing; within the tail of the plane or helicopt'er; a'solid metal rod 'or" reflector I? 9| mounted in an insulatingblock 92 soas not to be grounded, as shown in dottedlines in Fig. 10 11--i Forzplanesma-ving. a tail orsr'u'dder structure,

theaantenna fcan be :mounted'soithatisuch structurewillcserizeithis.purpose-equally as well as 'lttwillpofvcourse', be'apparent that 1 gmeans-(need not ibeset sothat the iiniiexin' pipjsinormallymoincidentwithfgraduation but infin'o'rmal use -ishis portionof; the circular trace issnotdmportantiforzclearance ordirectioniindicating purposes. 1 r ifdesired pairsof suitably connectedleads 92 "93, 94, and 95 respectively may bebrought out of'thetransformer foutputjamplifier 52,- and the high" gain amplifier 51to'the range-switch 96 -which ma y be mounted on the instrument panel 23and provided-With a suitable manipulable. key 25 91 5'Ih'etransformeroutput amplifier '52 is=convenientlyarranged*so-"thatiwhen the range switch '96 is in one position only -strongsignals fro'm relatively-'short range can b'e-imposed-uponthedefocusing'an0de42 and correspondingly the output "of the highgain-ampl-ifir 51 will be raised 'so thatrjthe' visible portion of thehorizontal trace as 'it appears-on: the *screen erid 3 3 of the cathode:ray tube 32 Will -represent a'distance of only aa-few hundred-yards.-"Consequently, jthe -lappa'ratus 3b will have what may beter-med shortrange and ma y be used immune landings and; take offs.

In additiomsuchshort range may be used before take offto check theaccuracy or the apparatus by taking a fix upon nearby ob'jectsof known40?position:and 'distancei By moving-the key' 91 to *5 its otherpo'sitiong the apparatus can bereturned 0 long range condition fornormalflighttopera- -21 tionv i 7 rtrwiu, :of course, be iinderstood'that modificationmaybe made' in'the apparatus without departing from-the spiritof 'our invention; For examplep the azimuthalondirectiomindicating race need not be circular in shape but {may beelliptica'l or 'diarnondfshaped and, fact; we m-ay even employ alinealtrace focused so as to =sbe spaced: from the distanceindicatingtrace for ease in readingj'it being obvious that in such instan'cestheaccompanying scales or graduations must beappropriately arranged onthe''face of the=screen-end of- 'the cathode: ray-tube; Simi- =lar1y; we mayemploy any high frequency radia- -tion" ranging ffrom' about 30-megacycles to 3000 megacycles or higher dependingupon the desired rangean d the permissible limits of weight, size and costwithinwhich:theeq'uipmen't is to be designed.

We 'cla'im: :-1-== An"'indicatin-gdevice comprising a bi-coni- 1 calhorn 'type ra'diator for-emittingradiant energy'impulses which-willeradia'te to produceimpulse echoes 1 upon 1 st king-a -remote object, al v rotating ant'ennai for receiving isuch impulse echoes, a cathode-ray:tube, having. ascreenand means fore-producing an elec'ztron beam; means-for--'causing--' the beam -to---':sweep first a circular trace :andthen al-inealtracevin sufliciently rapid successiontotake advantage ofthe persistence 'of human vision so I as to givethe :visualiappearanceoftwoyseparate andcontinuous images of the traces on the screenpmeansfor-imposing re- II ceived impulse echoes upon the tube to produce, 'onthe circular trace a'visible indication,

which, by its'position designates the direction of the object causingthe impulse echo, and means for imposing received impulse echoes uponthe tube to produce, on the lineal tracefla visible indication whichdesignates the distance between the source and the obstacle causing theimpulse echoes.

2. An indicating device comprising a bi-conical horn type radiator foremitting radiant en- I ergy impulses which will reradiate to produceimpulse echoes'upon striking a remote object, a rotatable antenna arrayconsisting of a dipole witha corner reflector for receiving such impulseechoes, a cathode ray tube having a screen and means for producing anelectron beam, a sine-wave oscillator for causing the beam to sweep acircular trace on the screen, means for rotating the antenna in timedrelation to the rate at which the beam sweeps the circular trace, asaw-tooth oscillator for causing the beam to sweep a lineal trace, meansfor alternately imposing the sine-wave oscillator output and the causingthe impulse echo, and means for imposing; received impulse echoes uponthe tube to produce on the lineal trace, a visible indication whichby-its position, designates the distance between the source and theobstacle causing the I impulse echoes. I 3. An indicating devicecomprising a means in- I cludingbi-conical horn type radiator foremitting'radiant energy impulses which will upon I striking a remoteobject reradiate to produce an impulse echo that returns alongthe'azimuthal "line between the radiator and such object, "a rotatableantenna having a line of directional receptivity and being adapted toreceive an impulse echo only when its line of directional receptivity issubstantially aligned with the azimuthal line along which the impulseecho returns,

" a cathode ray tube, having a screen and means I ing the impulseechoes.

" striking a remote object, a rotatable antenna array consisting of adipole with acorner reflector a receiver connected to the antenna,acathode ray tube having a screen, defocusing anode and means forproducing an electron beam, a sinewave oscillator for causing the beamto sweep a circular trace on the screen, means for rotating the antennain timed relation to the rate at which the beam sweeps the circulartrace, a saw-tooth oscillator for causing the beam to sweep a linealtrace, an impulse selector including a plurality of blanking means foralternately imposin the sine-wave oscillator output and'the' saw-toothoscillator output upon the beam in rapidsuccession to produce a visualefiect of simultaneous and continuous circular and lineal traces on thescreen, and switching mean for imposingthe receiver output upon thedefocusing anode when the beam is sweeping the circular trace to producea visible indication, which, by its position, designates the directionof the object causing the impulse echoes, said switching means beingalso adapted to superimpose the receiver output I upon the saw-toothoscillator when the beam is I sweeping a lineal trace, to produce avisible deflection which by its position designates the distance betweenthe source and the obstacle caus- 5. An indicating device comprisingmeans including abi-conical horn type radiator for emitting radiantenergy impulses which will, upon strikin a remote object, reradiate toproduce an impulse echo that returns along the-azimuthal I line betweenthe radiator and such object, a r0- tatable antenna having a line ofdirectional receptivity and being adapted to receive an impulse echoonly when its line of directional receptivity is substantially alignedwith the azimuthal line along which the impulse echo returns, a cathoderay tube having a screen and means for producing an electron beam,asine-wave oscillator for causing the beam to sweep a circular trace onthe screen, said screen being provided with anindexing mark adjacenttothe circular trace, a saw-tooth oscillator for causing the beam to-sweepa lineal trace means for blanking out first one oscillator and then theother in rapid succession so that both traces will continuously appearon the screen, means for rotating the anfor producing an electron beam,a sine-wave I tenna in timed relation to the rate of movement of thebeam as it sweeps the circular'trace, means for imposing receivedimpulse echoes upon the I tube to produce, on the circular trace, avisible then the other in suificiently rapid succession to I I tionwhich by its position designates the'distance take advantage ofthe'persistence of human vision so that both traces will appear on thescreen as continuous images, means for rotat ing the antenna in timedrelation to the rate of movement of the beam as it sweeps the circulartrace, means forimposing received impulse I echoes upon the tube toproduce, on the circudesignates the distance between the source and theobstacle causing the impulse echoes.

4; An indicating device comprising means including a bi-conical horntype radiator for emitting intermittent radiant energy pulses which willreradiate to produce impulse echoes upon;

indication; which, by its position, designate the direction of saidazimuthal line, means for imposing received impulse echoes upon the tubeto produce, on the lineal trace, a visible indicabetweenthe source andthe obstacle causing the impulse echoes, and means associated with therotatable antenna for producing a' visible indication on the circulartrace in registration with the indexing mark so long as said timedrelation is maintained.

6. An indicating device comprising means including a bi-conical horntype radiator for emit- I ting radiant energy impulses which will, uponstriking a remote object, reradiate to produce an impulse echo thatreturns along the azimuthal line between the radiator and such object, arotatable antenna having a line of direction receptivity and beingadapted to receive an impulse I echo only when its line of directionalreceptivity is substantially aligned with the azimuthal line along whichthe impulse'echo returns, a cathode ray tube having a screen and meansfor producing an electron beam, a sine-wave oscillator for causing thebeam to sweep a circular trace on the screen, said screen being providedwith an indexing mark adjacent to the circular trace, means for rotatingthe antenna in time relation to the rate of movement of the beam as itsweeps the circular trace, means for imposing received impulse echoesupon the tube to produce, on the circular trace, a visible indication,which, by its position, designates the direction of said azimuthal line,impulse producing means carried by the rotatable antenna, and meansmounted in proximity to the impulse producing means, said means beingadapted to receive an impulse from the impulse producing mean as thelatter passes over a predetermined position, said impulse being imposedupon the cathode ray tube for producing a visible indication on thecircular trace in registration with the indexing mark so long as saidtimed relation is maintained.

'7. An indicating device comprising a bi-conical horn type radiator foremitting radiant energy impulses which will reradiate to produce impulseechoes upon striking a remote object, a continuously rotating antennafor receiving such impulse echoes, a cathode ray tube having a screenand means for producing an electron beam, means for causing the beam tosweep first a circular trace and then a lineal trace in sufilcientlyrapid succession to take advantage of the persistence of human vision soas to give the visual appearance of two separate and continuous imagesof the traces on the screen, means for imposing received impulse echoesupon the tube to produce, on the circular trace a visible indication,which, by its position designates the direction of the oh- 14 jectcausing the impulse echo, and means for imposing receivedimpulse echoesupon the tube to produce, on the lineal trace, a visible indicationwhich designates the distance between the source and the obstaclecausing the impulse echoes.

LEONARD B. LIPSON.

- ALFRED W. PETCHAFI.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 2,151,917 Hyland Mar. 28, 19392,175,252 Carter Oct. 10, 1939 2,189,549 H ershberger Feb. 6, 19402,216,950 Kummich Oct. 8, 1940 2,272,607 Higonnet Feb. 10, 19422,283,935 King May 26, 1942 2,312,761 Hershberger Mar. 2, 1943 2,405,2311 Newhouse 'Aug. 6, 1946 2,409,462 Zworyking Oct. 15, 1946 2,412,702 'j'vvqifr Dec. 17, 1946 2,419,205 Eeldman Apr. 22, 1947 2,419,567 LabinApr. 29, 1947 2,422,361 Miller June 7, 947 2,430,292 Hershberger Nov. 4,1947 2,449,976 Bu'signies Sept. 28, 1948 2,468,032 Busigm'es Apr. 26,1949 FOREIGN PATENTS Number Country Date 497,147 Great Britain Dec. 9,1938 542,634 Great Britain Jan. 21, 1942

